Britain sent a peace mission to Bhutan in early 1864, in the wake of the recent conclusion of a civil war there, under Ashley Eden.[1] The dzongpon of Punakha – who had emerged victorious – had broken with the central government and set up a rival Druk Desi while the legitimate druk desi sought the protection of the ponlop of Paro and was later deposed. The British mission dealt alternately with the rival ponlop of Paro and the ponlop of Tongsa (the latter acted on behalf of the druk desi), but Bhutan rejected the peace and friendship treaty it offered. Britain declared war in November 1864. Bhutan had no regular army, and what forces existed were composed of dzong guards armed with matchlocks, bows and arrows, swords, knives, and catapults. Some of these dzong guards, carrying shields and wearing chainmail armor, engaged the well-equipped British forces.

Ashley Eden forced by the Bhutanese to sign a Treaty, 1864. Illustration by A.D. Macromick (1909)

Storming of Dewangiri

The fort, known at the time as Dewangiri, at Deothang was dismantled by the British during 1865. The British initially suffered a humiliating defeat at Deothang and when they recaptured Dewangiri they destroyed much in an attempt to compensate.

The Duar War (1864–1865) lasted only five months and, despite some battlefield victories by Bhutanese forces, resulted in Bhutan's defeat, loss of part of its sovereign territory, and forced cession of formerly occupied territories. Under the terms of the Treaty of Sinchula, signed November 11, 1865, Bhutan ceded territories in the AssamDuars and BengalDuars, as well as the 83 km² of territory of Dewangiri in southeastern Bhutan, in return for an annual subsidy of 50,000 rupees. The Treaty of Sinchula stood until 1910, when Bhutan and British India signed the Treaty of Punakha, effective until 1947.

Treaty between His Excellency the Right Honourable Sir John Lawrence, G.C.B., K.S.I., Viceroy and Governor-General of Her Britannic Majesty's possessions in the East Indies, and the one part by Lieutenant Colonel Herbert Bruce, CB, by virtue of full powers to that effect vested in him by the Viceroy and Governor – General, and on the other part by Samdojey Deb Jimpey and Themseyrensey Donai according to full powers conferred on them by the Dhum and Deb Rajahs, 1865.

ARTICLE I There shall henceforth be perpetual peace and friendship between the British Government and the Government of Bhootan.

ARTICLE II Whereas in consequence of repeated aggressions of the Bhootan Government and of the refusal of that Government to afford satisfaction for those aggressions, and for their insulting treatment of the officers sent by His Excellency the Governor-General in Council for the purpose of procuring an amicable adjustment of differences existing between the two states, the British Government has been compelled to seize by an armed force the whole of the Doars and certain Hill Posts protecting the passes into Bhootan, and whereas the Bhootan Government has now expressed its regret for past misconduct and a desire for the establishment of friendly relations with the British Government, it is hereby agreed that the whole of the tract known as the Eighteen Doars, bordering on the districts of Rungpoor, Cooch Behar, and Assam, together with the Taloo of Ambaree Fallcottah and the Hill territory on the left bank of the Teesta up to such points as may be laid down by the British Commissioner appointed for the purpose is ceded by the Bhootan Government to the British Government forever.

ARTICLE III The Bhootan Government hereby agree to surrender all British subjects, as well as subjects of the Chief of Sikkim and Cooch Behar who are now detained in Bhootan against their will, and to place no impediment in the way of the return of all or any of such persons into British territory.

ARTICLE IV In consideration of the cession by the Bhootan Government of the territories specified in Article II of this Treaty, and of the said Government having expressed its regret for past misconduct, and having hereby engaged for the future to restrain all evil disposed persons from committing crimes within British territory or the territories of the Rajahs of Sikkim and Cooch Behar and to give prompt and full redress for all such crimes which may be committed in defiance of their commands, the British Government agree to make an annual allowance to the Government of Bhootan of a sum not exceeding fifty thousand rupees (Rupees 50,000) to be paid to officers not below the rank of Jungpen, who shall be deputed by the Government of Bhootan to receive the same. And it is further hereby agreed that the payments shall be made as specified below:

On the fulfillment by the Bhootan Government of the conditions of this Treaty Twenty Five Thousand Rupees (Rupees 25,000).

On the 10th January following the 1st payment, thirty five thousand rupees (Rupees 35,000)

On the 10th January following, forty-five thousand rupees (Rupees 45,000)